Code rearrangment
Added instance_id(Obj) to Prolog arith expressions
Included metastrategies.prolog in load list

D’oh!
Added unit tests for strategy matching
Refactored default conflict metastrategies

Now phrased as actual defaults.
Small change in object position

For some reason, Unity didn’t save this change before.
Fixed check for existence of strategy preference

Now uses clause/2 to search for it in case the preference
implementation doesn’t handle being called with uninstantiated
arguments.
Merge pull request #2 from ianhorswill/master

Updates